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(No Model.) 3 Sheets-Sheet 1.

L. BOLLMANN. APPARATUS FOR TRANSFORMING ELECTRIC GURRENTS. No. 365,116. Patented June 21,-1887..

FIG. 2. H51.

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(No Model.) 3 Sheets-Sheet 2.

L. BOLLMANN. APPARATUS FOR TRANSFORMING ELECTRIC GURRBNTS.-' No. 365,116. Patented June 21, 1887..

FIG. 4.

ZZZ/messes V gventarr UNITED STATES PATENT 7 OFFICE.

LOUIS BOLLMANN, OF VIENNA, AUSTRIA-HUNGARY, ASSIGNOR OF ONE-HALF TO ERNEST BIEDERMANN AND DEMETER MONNIER, BOTH OF SAME PL AGE.

APPARATUS FOR TRA'NSFORMING ELECTRIC CURRENTS.

SPECIFICATION forming part of Letters Patent No. 365,116, dated June 21, 1887.

Application filed April 20, lfrr'fi. Serial No. 199,495. (No model.)

To (LZZ whom, it may concern.-

, Be it known that I, LoUIs BOLLMANN, manufacturer, a citizen of the United States, and a resident of Vienna, in the Empire of Austria- Hungary have invented certain new and useful Improvcmentsin the Method of and Apparatus for Transforming the Conditions of Electric Currents, of which the following is a specification.

My invention relates to iinproven'ients in the method of and in apparatus for transforming continuous electric currents from a high tension to a continuous current of alower tension by the combination of electromagnets with a commutator or its equivalent, which divides the several coils of the said magnets into two separate circuits, one conveying the primary current of high tension to a number of the said coils joined in series, while the other (circuit) is connected with the remaining coils joined in parallel. The primary current passes, therefore, through the coils in its circuit from one to the other in series, and thereby magnetizes and demagnetizes the iron intermittently or J alternately, while the secondary current (thereby induced in the other coils of the same magnets) passes off from each coil in parallel into the secondary circuit, which keeps it at a low tension. The arrangement is such that 0 both the primary and the secondary currents flow successively in each coil, but always in the same direction.

The novel features of my invention will be hereinafter described, and definitely set forth 5 in the claims. A

In the accompanying drawings, wherein my invention is fully illustrated, Figure 1 is a side view, and Fig.2 a plan view,of one of the elcetro-magnets. Fig. 3 is an elevation of the 0 comnutator with part of the frame shown in section. Fig. 4 is a longitudinal section of the same through the center line :0 0c, and in the lower part through the line g y in Fig. 3. The other nine figures are'details and diagrams, 5 which will be fully described hereinafter. I

The elcctro-magncts, Figs. 1 and 2, consist of iron rods A A, connected on both ends to solid iron plates 13 B, so as to form a ringmagnet or a closed magnet. Therods arc covered by several layers of insulated copper wire, forming coils, which are connected, as will be explained hereinafter. It may here be mentioned that the arrangement and form of these magnets form no part of this invention, and any-other construction may as well be used. In the diagram, Fig. 10, are shown eight pairs of such magnets placed side by side.

Figs. 3 and 4 show the arrangement of the commutator, whose rotating parts are connected to the shaft 0, bearing in the frame D, Go and which is driven at proper speed by any convenient power,or by the principal current, as will be hereinafter described.

E E E E" are four metal rings fastened to the shaft 0, so that each of them is insu- 6 latcd.

L are coppersprings bearing slightly on the rings, and acting as brushes to transfer the eu rrents to the rotating parts and away from them. Any other form of brushes may be used. c

F F are drums, of-wood, (or othcrinsulat ing material,) to which the metal ring-sections Gr G H H J J J J are fastened. The mutual arrangement of these sections is shown in Fig. 12, showing the circumference of the same from s to t, stretched out fiat. Against this circumference bear sixteen brushes, K, which are distributed around the circle in eight pairs, as is shown in Fig. 3. Fig. 12 shows the situations of the bearing-surfaces of So these brushes, they being drawn with hatching-lines. The short parts G1 G, Fig. 12, (of which in the Figs. 3 and 4 only G is seen,) are each connected with one of the rings E and E by means of copper wires Z, which are in- 8 5 sulated and pass between the shaft and the inner rings, E and E, as is seen on the left side of Fig. 4.

Only one of the copper wires Z can be seen in Fig. 3, and at the left side of the ring-sego inent E, Fig. 4. The other one belonging to the segment G, which stands at a right angle to G on the right side of Fig. 4, cannot be seen. In Figs. 10, 11, and 13 both wires Z Zare indicated. 9 5

The segments H H, which form the larger part of the circumference, are similarly connected by pieces H to the inner rings, E and FF", and the plates L, bearing on these rings, are in connection with the cables forming the secondary circuit, and which lead the induced low-tension current from the ring E" through its spring-plates L to the lamps and return the same again to ring E. In the same manner are the two outside rings, E and it, connected by their plates Ii, so that the current entering at IE will pass G and thence to G", and from it to and through E The spring-plates L are fastened to the wooden cross-pieces D, which form part of the frame I).

The four narrow segments J J .I J, Figs. 12 and 1.3, are in pairs connected by copper rods 12. 11, passing below from one to the other, J and J' forming one pair and .I and J the other. The spaces between the segment parts are filled out with some suitable non-conducting substance.

The dynamo-machines having a large number of field-1nagnets, it is desirable that the collector-brushes should be narrow, and that the surface of contact with the collector should not alter in situation nor in width when it wears off. This is accomplished by the con struction shown in Figs. 5, 6, and 7. brush K consists of thin elastic strips or wire, which I preferto fasten in bundles into notches cut into the body 7., as shown in the side View, Fig. 6. They stand at an angle (of say fortyiive degrees) to the axis of the collector, Fig. 4-, but in radial direction when seen from the front, Fig. 3, and they are fastened between two metallic plates forming the brush-holder K, so that they can be adjusted more or less outward in the angular direction when their hearing surfaces wear away. These plates reach near to the collector, in order to prevent the strips bending sidewise, and also to assist in leading away the current,which prevents heating.

The lnush-holder bears on a shaftor pin,l\[, on which it can swing freely, and a spring, 0, holds the brush to the collector. The springs for the brushes are shown in Fig. 3. Thesesprings consist of elastic strips 12 of india-rubber or of insulated spiral springs,

which are stretched between proper projections, w, of two brush holders and press the brushes K K against the commutator. The angular position of the strips causes the brush to bear softly on the collector, and they must remain in, the same situation and of the same breadth after their surfaces have been worn away. In other brushes having the flat sides of their strips parallel with the axis of the collector those strips next to the edges of the brush, which glide off the last from the colleetor'bars will always burn away first, because these have to carry the short-circuit current, which is formed more or less every time when the points of these brushes leave or glide off the collector-bars, and which is the cause of the sparks. In this brush the flat surfaces of the strips are parallel to the circumference of the collector.

The

Therefore those short circuits are taken off by the entire body of the brush, each strip re ceiving an equal share of it. This dimiir ishes to a great extent the sparks and the heating and wasting of the brushes and collector. There are four such holders bearing on each of the four rods M, and they are so disposed that their faces bear on the commutator in rows at equal distances from each other, as seen in Figs. 3, -.l-, and 5. This dcscription relates to the entire sixteen (1.6) brushes. In Fig. 3 only eight (8) of the brushes can be seen,beeause the back ones are covered by those in front, for they are parallel to the latter, as will be understood by refererence to Fig. 12. In Fig. -ct two brushes are shown as bearing (in the upper part) on the segments, while two others on the same rod M, being behind, are only indicated by dotted lines to explain their inclined position in relation to those in front. Each pair of brushes occupies relatively the same position as those shown in Fig. i, and they are disposed in eight equal divisions around the circle, as shown in Fig. 3. The brushes at the bottom of Fig. 4 are only partly shown.

Each brush-holder is connected by a flexible cable, as indicated by I in Fig. 3, to one end of the coils ofthe magnets. Those situated on the drum F are marked with the sign In the brushes marked the currents pass from the commutator to the brush, and vice versa in those marked with In Fig. 3 we have shown eight (8) cables. All brushes and cables seen in Fig. 3 are of sign, according to the diagrams Figs. 10 and 11, while those situated behind, aml therefore covered or obscured by them, are of the sign. In Fig. I all brushes and cables on the right side are of the sign, and those at the left side are of the sign.

The connections of the coils of the magnets are illustrated by the diagram Fig. 10, in which the circumference of the commutator and the bearingsurfaces of the brushes are drawn narrower than in Fig. 12.

In the diagram Fig. 1.1, the segment G, which is in connection with the principal cur rent, as above explained, is bearing on the brush. marked (1+, and this is connected by a wire conductor to the coils of the magnet-rod, marked also a-I-. The latter coils are connected to the coils of the rod 1.4-, which again is connected to the brush c-, that bears on the segment .1. In like manner is the brush b+ connected with coils b t, and this with the coils I), which again is connected with the brush b-, resting on the segment J, and so are each following pair of brushes connected with the rods marked with the same letters.

It is to be remarked that the two magnetrodshavingsimilarletters (as (1+, (4*, b b-, the.) do not belong to one ring'magnct, but to two different ones standing side by side,and that the connections of the coils are such that the currents must flow in. each succeeding one in IIO the opposite direction, so. that when all would be equally magnetized there would appear no free magnetism anywhere.

Suppose the commutator to rotate so that the circumference is moving in the direction of the arrow Z. The principal current is supposed to how through Z toward the segment G and to pass to brush a+, then to the coils of a+ and (1+ back to the brush a+ and segment J From there it is passed over to the segment J (through the rod at below the surface,') from where it again flows through brush b+, coils b+ 12+, brush b+, to segment J. Then again through the rod n to segment J from where it circulates through brush 0+, coils 0+ 0 brush 0+, to the segment G, from which it passes away to the principal cable through Z.

The principal current flows,therefore, through the coils a+ 0+ 5+ b+ 0+ 0+, and magnetizes the rods to the required degree. As the commutator moves on, the segments change positions in relation to the brushes, so that, for example, in the position shown by the diagram, Fig. 11, the segments G' G are nearly leaving the brushes a+ and 0+ while they are already covered by those b+ and (2+, so that the principal current is never interrupted. In going 011 farther the segments G G will come in relation to the brushes b+ and dinto the same positions as they were before to 11+ and 0+, and the latter (a+ and 0+) will have passed out of contact'with the principal circuit and got into contact with the long segments H H, which are connected by the parts H with the secondary circuit. Thus the brushes to the right of segment G are coming newly in connection with the principal circuit, and the magnets belonging to them are newly magnetized, so long until they get to theleft side of G when they come out of connection with the principal and into contact with the secondary circuit again. The bars h+ h+ were thus previously magnetized, and are nowdemagnetized, which causes theinduction of a secondary current in the coils surrounding them of similar direction with the principal current that has magnetized the iron. This secondary current flows over through the brush it to the segment H, and then through H into the cable leading to the lamps, rcturning thenthrough H to complete the circuit, and as the commutator rotates farther on new brushes come from the principal into the secondary circuit, so that in the arrangement illustrated there are constantly siX of the magnetrods connected with the principal and ten of them with the secondary circuit; but while the first mentioned six coils are connected with each other in series+that is, one after another+thc latter ten are connected with the secondary circuit in parallel-+that is, side by side. The magnetizing consequently takes place while three pairs of coils are con nected in series, and the demagnetizing while five pairs of coils are united in parallels.

If the resistance of one pair of coils is r, then that of three pairs in series is equal to 31', and of five pairs in parallel it is g The difference of both resistances is therefore as 3r to g, or as one to fifteen, and this causes the tension of the current induced to be much less than that of the principal. It is obvious that the quantity or intensity of the current induced is in inverse proportion to its elcctromotive force.

At the moments when the segments G G leave a brush the current tends to flow on while the iron is beginning to be demagnet ized. This is liable to produce intense sparks, and this would be especially the case if the coils connected to one pair of brushes, for example, a+ and a, were belongingto the same closed ring-magnet; but as the rods a+ audabelong each to another circle or ring-magnet, the sparks are very much reduced, for the rod h+, belonging to the same ring-magnet to which belongs a+, has been previously discharged, and the principal current is only passing through the legs of a+. The magnetic moment of the entire ringmagnet is therefore now only one-half of that which it would be if both rods h+ and a+ were surrounded by the magnetizing eurrent, for it is proved by experiments well known that in rings the magnetic moment is practically at every place of thecircle the same wherever the magnetizing-coil may be situated. \Vhile previously both bars hand (0+ were magnetized, (as are now those a+ and b+,) the magnetic moment was of course double thatit is now after it has been disconnected, and if new a+ is disconnected, the magnetism is vanishing as well in h+ as in (0+. Consequently the induction due to the remaining (one-half) n'iagnetism is now divided between the coils of h+ and a+, so that for this reason the tendency to produce sparks is reduced to one-fourth. The other rod, (1+, belonging to the same pair of brushes, can also not demagnetizc now fully, because its partner 5+ is still being magnetized. The entire iron of this ring can consequently be demagnetized at most to one-half, and only onc-half of the induction due to this reduction can act on the I coils b+, tending there to strengthen the principal current. By this arrangement of connecting the coils belonging to the rods of two different ring-magnets, the tendency to produce sparks is therefore greatly reduced.

To make the flow of the principal current still more smooth and constant, a larger number of magnets of less dimensions may be used. Then the brushes would have to be disposed so that two brushes are constantly bearing on the segments G G, and morethan four segments J, connected by rods n, would have to be placed side by side. The principal current would then flow in two series, which are connected two in parallel. The

sparks would be still more reduced if more than two rods are connected to form one closed circle and these connected with the brushes in such a manner that each pair of the latter has connection with rods belonging to different magnetic circles.

In the above described arrangement the magnetism of those rods whose coils are connected to the segments II ll. that belong to the secondary circuit can be discharged only so far that the energy of induction by its vanishing is yet capable of producing an electro motive force in the surrounding coils, which corresponds to the number of volts required for the secondary current; for if vanishing (or demagnetization) of the magnetism has no longer the energy'to induce a current of that tension, the current from the other coils, also connected to H II", would flow backward through this coil, instead of going through the lamps.

\Vhen a coil passes from the principal into the secondary circuit, (at the left side of G,) the vanishing of the magnetism and thcinduction in the coils are at first energetically; but afterward these actions are gradually slack ing oil, the more so as the current flows in these coils in the same direction as the principal current was flowing before, which tends to retard the demagnetization.

To make theapparatus capable to discharge the entire magnetism,and otherwise to increase its power, the following modification may be used, which is illustrated in Fig. 13. There are as many pairs of brushes connected in series with the principal as there are in parallel con neeted with the secondary circuit. Therefore six (instead of eight) ring-magnets and as many pairs of brushes are shown, three pairs being in series and three pairs in parallels. There are now two separate coils on each magnet-rod. The wire connection from thepositive brushes is as :follows: commencing with brush at, which is in contact with G, the wire passes first to the lower coil on the rod (1+, to which it is connected in such a way that the current coming from the brush (t-lmust ilow in opposite direction to that before described. The other end of the coil (1+ is connected with the lower coil of the rod d-, belonging to the next magnet circle also in opposite direction, so that the current must low opposite to the current which passes to the upper coil of wt, and then through the upper coil of ain the same direction as has been described for the first arrangement. In the same way is the wire of brush b+ passed first around the lower rods, 0+ and c, both in opposite direction, and then around the upper rods, 11+ and b-, and to the brush b, and so on in the following order: brush 0+ with lower coils off+ f-, then with upper coils of 0+ c, brush (l -l with lower coils of (Ii-l a-, then with upper coils ofd t (Z--,brush c-lwithlower coils ofl lb, then theupper coils of ('-t c-, brushf+ with the lower coils of c-|-- 0-, and then to the coils of f t-f In the two coils of the same rod is the direction of the currents opposite to one another, as is indicated by the short arrows of the coils, and one is connected with the principal circuit, while the other is in the secondary, both changing circuits at the same moment.

Vhen the brushes f+f are changing connections bypassing from the segments G and J over to H II, the brushes 0 c are also changing from II ll to J' and G". Now, the magnetism of the rodsf +f commences to vanish and induce in the upper coilsa current of the same directions as previously the principal current was flowing in them. time the lower coils off [-f-, which come in connection with the brushes 0 0 receive from brush c ttheprincipal currentin opposite direction. This tends to magnetize the rodsin the opposite sense, and accelerates the demagnetization, and when this is completed magnetizcs the iron in the opposite sense, inducts in the upper coils in the same direction, and the current thus inducted passes into the secondary circuit. Vhen these brushes have reached the positions of d d the iron will be oppositely magnetized to the same degree, as before, by the principal current in the lower coils, and when passing into the position a "l a the upper and lower coils again change contact. The lower coils have now contact with the brnshesf f into the secondary circuit, and the upper ones receive the primary current, which from thelower coils off and f which are in contact with the brush 0 Theyare then at first demagnctizing and then magnetizing in the same way,but in opposite direction, as before described, for the rods f+f until the brushes reach again the positions a -ta In every coil the current flows in all positions of the brushes always in the same directions, only the circuits with which they are connected changing alternately; but the magnetism is alternately changing its polarity. Thereby the energy ot'induction and the power of the apparatus will be much increased and be more than four times of that produced by single coils.

The current induced must always tlow through four coils (through two upper and two lower ones connected together) before it flows off. This reduces the intense action of induction at the first moments of discharge, because this strong current tends to retard the demagnetization of the iron, so that the current will flow constantly.

In order to reduce the sparks on the brushes, which are caused while the brushes pass from the principal into the secondary current, the combination may be such that the second coils of the same magnet-rods do not receive the op posite principal current at that moment, but afterward, so that the demagnetization by the opposite current may commence after the brushes have passed into the secondary current. This may be accomplished by using seven instead of six pairs of magnets and brushes, three of which are always in the principal and four in the secondary circuits. The wire coming from the brush a passes then one pai r of rods farther to the right than. shown in Fig. 13-viz., to the lower coils 0+ instead of (1+, and so on, every other wire coming At the samefrom the positive brushes. Now, when brush (0+ passes over to position h+, the lower coils 6+ e, then connected to it, pass into the secondary circuit; but the upper coils 6+ e-, (which have connection with the brushes 6+ e through the lower coils b+ b remain yet in the secondary circuit.,The magnetism of the rods 0+ 6- is therefore discharging now by its own energy, (which is limited by the connection of these rods to the rods dandf-,) as before explained. As the brushes pass then farther on,those 0+ ereach the principal circuit at G and J but the brushes (H- arest ing then already fully on the segments H II, there can appear no sparks on that account.

In general, every induction ofa current involves the induction of a second current of the same intensity in an opposite direction, which causes alternating currents in the conductor or in the coils which arewithin the influence of the inducing magnet or current. This is also the case in this apparatus; but matters are here so arranged that the second and opposite currents are always extra currents started within the principal circuit and opposite to it. They equalize an equal quantityof energy of the principal current, which represents the equivalent of dynamic force transformed as secondary current. The consequence of this is that the opposite currents never come to existence as such, but consume the principal by being united with it. If another power is not conveniently at hand, the shaft 0 may be driven by a little electro dynamic motor attached to it. Figs. 8 and 9 show a method to produce such a motion. On the end of the shaft 0 is fastened the iron arm It,

into one end of whieh are fastened two rods,

of iron wound with coils, and forming an open electromagnet. The other end is of some other metal, and serves as counterweight. The wire ends of the coils pass through a hole in the center of O, and one end is connected in shunt to the ring E and the other to E,Fig. 4,so that a part of the principal'current must pass through the coils of R.

S are eight small electromagnets, disposed in circle so as to correspond with the rotating one, It, as shown. Their ends of wire are connected each to one of the brushes of same letters, also in shunt,'and so that the magnets S and R always repulse each other.

Now, the currents of the brushes vary in strength at the point where one passes from the secondary into the principal circuitthat is, in Fig. 10, between 0+ 0- and (1+ d, and the connection must be such that the rotating magnet vR always stands just opposite that one of the magnets S which is in connection with the brush that is making that change of po sition. The magnet R will then be repulsed less during the approach than during the retreat from that magnet, and this difference of force produces the required motion of the shaft.

By making the connections between the upper and lower coils in Fig. 10, one red farther apart-namely, from (0+ to (1+ instead from a] to c, as explained, the difference of the intensity of current will be greater and the power of driving the shaft more energetic.

Having described my invention and the inethod of its actions, I desire to state that I do not confine myself to the particular form and construction and connections of the mag nets and of the commutator herein described, which may be varied in many ways.

The numbers of the brushes, coils, and magnets must vary according to circumstances, as well as their dimensions and proportions.

I claim- 1. In apparatus for the transformation of electric currents, the combination, with primary and secondary circuits, of a series of closed eleetromagnets without open poles, a commutator whose plates are connected with the primary and secondary circuits, and brushes or contact-pieces connected with the electro-magnets, whereby the coils of the electro-magnets are connected at one period with the primary circuit for charging and at another period with the secondary circuit for discharging.

2. In apparatus for the transformation of electric currents, consisting of a series of closed electromagnets, a commutator provided with positive and negative movable sections G J H, connected to the primary and secondary circuits, combined with brushes connected with the coils of the apparatus in the order described ,whereby the connections of the coils are successively transferred from one circuit to the other without interruption of either current, and also whereby in each coil both the primary and secondary currents flow alternatelyin one and the same direction, substantiall y as shown and described. I

8. In apparatus for thetransformation of electric currents, consisting of a series of closed electro: magnets for the purpose of reducing the intensity of the sparks in the commutator, the combination, with each pair of brushes, of coils of electro-magnets that change circuits at different periods, as herein set forth.

4.. Two coils or sets of coils on each branch of the electro-magnets, in each of which coils pass, alternately, the primary and the secondary circuits in the same direction, but this direction being in one coil opposite that in the next coil, four of such coils being combined with each other and with one pair of brushes, essentially as shown and described, and in order to increase the intensity of induction.

Signed at Vienna, in the Empire of Austria- Hungary, this 26th day of March, 1886.

LOUIS BOLLMANN.

Witnesses:

EDMUN J USSEN, OTTO SOHEFFER. 

